Hydrocarbon oils of reduced foaming properties



United States P 3,166,508 HYDROCARBGN 0115 OF REDUCED FGAMING PROPERTIES Joseph E. Fields, Baliwin, Mm, assignor to Monsanto Company, a corporatipn of Delaware No Drawing. Fiied Jan. 16, 1963, Ser. No. 253,717

' 16 Claims. (1. 252-515) This invention provides hydrocarbon oils which are rendered antifoaming by the incorporation therein of certain polymeric acrylates.

In recent years the foam suppression of hydrocarbon oils has become of major importance owingto new developments 'in engine construction and use of foaminducing additives. Attempts to solve the problem by defoaming existing oils using mechanical or physical means, e.g., by submitting them to heat treatment, absorption or filtration have proved of but little value. The most practical solution to this problem has been achieved by the use of antifoam additives.

Additives are currently added to hydrocarbon oils for many purposes. Advantageously, in the art, the additive performs a specific task when incorporated into the oil. An anti-corrosive additive preferably affects only the corrosive properties of the oil; a detersive additive, only l the detersive properties; an extreme-pressure resisting additive, only the pressure-resisting properties; a viscosity index improving agent, only the viscosity properties; and an antifoam agent, only the antifoaming properties; Hydrocarbon oils, e.g., lubricants and motor-fuels are custom-tailored to serve well-defined needs and it is only by the careful blending of additives having individual functions that a properly compounded oil can be arrived at and successively duplicated.

An object of the present invention is to provide a hydro-v carbon oil product containing an additive which will' V reduce and even completely eliminate the foam susceptibility of the hydrocarbon oil without substantially modifyingor altering other properties of the oil. Another object of the invention'is the. provision of an antifoam additive for hydrocarbon oils which is retained in said oil under divcrse operating conditions and, during long periods of storage. Still another object of the invention is the provision of an antifoam additive whichwill not react with other additives generally employed with said oils.' A further object of the invention is the provision a "of such an additive from readily available raw materials.

I have found that these objects and others which will V be hereinafter defined are provided by the present invention whereinthere is added to hydrocarbon oil compositions for the purpose of suppressing thefoaming tendency thereof, a small amount, less than 0.1% by weight based on the weight of said oil, sufficient to suppress said foaming tendency and insufficient to modify substantially the viscosity characteristics of the oil, of an alkyl acrylate 3,155,5h8 Eatented Jan. 19, 1965 "ice and have molecular weights of less than 10,000, usually less than 8,000 or 6,900, and preferably less than 5,000, 1

which are much lower molecular weights than those customarily employed to modify viscosityindex of oils.

In the prior art, polymeric acrylates have been added to hydrocarbon oils for the purpose of increasing the viscosity index thereof, for promoting adhesion of the oils to cylinders, for thickening oils to greases, etc. The

addition of acrylates to oils in order to bring about modi- I fication of the viscosity, thickening or adhesive properties of the oil required at least 0.1% and up to about 5% of wherein esters of polyhydric alcohols and long chain fatty acids are added to hydrocarbono'ils containing polymeric acrylates in quantities sufficient to improve the lubricating properties of the oil, said esters being added to such polymer-containing oils for the. purpose of suppressing the foaming tendencies thereof. The suppression of foam ing and emulsifying tendencies of hydrocarbon oils con taining from 0.1% to 5% of polymeric acrylates also forms the subject of.U.S. Patents Nos. 2,486,493 and 2,489,671 to Revukas wherein certain amino compounds or certain organic phosphorus compounds are used for this purpose.

In view of the fact that alkyl 'acrylate polymers have been reported to increase the foamsusceptibility when added to hydrocarbon oils in amounts from 0.1% and upwards, it is surprising that when the particular alkyl acrylate polymers specified herein are added to the same quantity of less than 0.06% by weight, based on the weight of the oil composition, are those polymers in which the alkyl chainilength has from 3 to 6 carbon atoms. Polymeric methyl acrylate, and polymeric ethyl acrylate are too oil-insoluble for the present purposes.

Polymeric propyl acrylate provides .a degree of oil-solubility which rend ers it effective as ,an antifoam agent, although its maximum antifoaming effect does not'appear at a concentration which is as low asthat at which the maximum antifoaming effectof polymeric butyl acrylate I and polymeric amyl acrylate is. found. For example,

polymer selected from theclass consisting of (A) a normally fluid homopolymer of an alkyl acrylate having at least} but less than 7 carbon atoms in the alkyl radical, (B) a normally fluid copolymer of at least two different alkyl acrylates in which the alkyl radical has froml to 18 carbon atoms and in which the average number of carbon atoms in the alkyl radicals of the copolymer' molecule is at least 3 but less than 7 on a molar basis and (C) a copolymer having the oil-solubility of (A) and containing atleast by weight of analkyl acrylate in which the alkyl radical has from 1 to 18 carbon atoms with the-balance being a compound other than said acry V late and copolymcrizable with'the acrylate. 'By normally fluid is meant thinly liquid to highly viscous polymers, the term fluidf'being preferred by the art to liquid in describing a viscous substance. Howi ever, in general polymers employed hereiniwill be liquid while polymeric butyl'acrylate completely suppresses the foaming of a certain hydrocarbon oil composition at a,

concentration of as little as say, 1 to 5 parts per million, polymeric propyl acrylate must be employed in" concentrations of as high as say, about 50 parts per million before the foaming tendency of the same oil composition is completely suppressed. Polymeric hexyltacrylate possesses foam suppressing effect but here, also, the con centrations at which it is useful differs from the con centrations at which polymeric amyl acrylate is useful, a greater quantity of this polymer .being required to give the same effect. As is known in the art, the Oil-solubility property of the polymeric alkyl acrylates changes with a change in the number of carbon atoms in the alkyl radical.

I have found that the antifoaming effect of alkyl acrylate polymers also varies with theoil-solubility of such polythat a pronounced antifoam effect is. demonstrated when such polymers are added to hydrocarbon oil compositions at concentrations of less than 0.1%. A higher member, i.e., polymeric n-octyl acrylate or Z-ethylhexyl acrylate is too oil-soluble, and the next-lower member, i.e., polymeric ethyl acrylate, is too oil-insoluble to possess antifoaming activity.

Acrylate-acrylate copolymers having the oil-solubility of homopolymeric acrylates may be obtained from mixtures of the lower alkyl acrylates, i.e., ethyl or methyl, and the higher alkyl esters such as n-octyl or dodecyl, provided that the average of the number of carbon atoms in the alkyl radicals of the ester mixture, based on molar proportions is at least 3, but less than 7, e.g., a copolynier made from a 70:30 mixture'of methyl acrylate and np ropyl acrylate has a carbon chain average of 1.6' and is not useful forthe present purpose, whereas a copolymer made from a 70:30 mixture of ethyl acrylate and Z-ethylhexyl acrylate has an average number of 6.2 carbon atoms in the total alkyl groups of the copolymer, and is a very effective antifoam agent. The average alkyl chain length in the copolymer molecule is extremely critical. The

. following table illustrates monomeric mixtures which When impart anti-foaming properties. On the other hand, such monomers as alkylated styrene, the higher alkyl (Ste 18 fcarbon atoms) methacrylates, the higher alkyl maleates or iumarates and vinyl esters of the higher aliphatic monogree of solubility. a

1 When the alkyl acrylate component isone having an alkyl radical of from 8 to l8carbon atoms, the co-monsubjected to polymerizing conditions yield normally fluid antifoaming copolymershaving an average chain length of from 3 to less than 7 carbon atoms on a molar basis Av. No. Carbon Lower 'Alkyl Mole Higher Alkyl Mole Atoms In Acrylate Percent Acrylate Percent Total Alkyl Group of Copolymer, Molar Basis Methyl acrylate 50 5O 5. 0 D0 40 6O 6. l 30 70 59 60 4O 3. 8 10 90 4. 6

5 95 V 3. 85' D0 63 37 5.07 Ethyl acrylate 3O 70 6. 2

Do 5O 50 6.0

60 40 5. 6 I soamyl. 80 4. 4 l8 n-Butyl s2 3. 64

It is preferred to employ alkyl acrylate polymers having atoms. As is known to those skilledin the art more than I two different alkyl acrylates may be polymerizedtogether 7 larly truewhen oils have a high paraffin content. For 7 such oilslthe' oil solubility ofeven the higher alkyl to give copolymers h'avingan average'of at least 3 but less than 7 carbon atoms in the total alkyl groups'ofthe copolymer..- Thus, there may be'used a'mixture consisting of 50 mole percent of methyl acrylate, 25 mole percent 1 .tures' containing the various acrylates in molar proper? tions calculated to give an average of at least 3 but less than 7 carbon atoms in the total alkyl radicals of the copolymer. v

Just as the oil-solubility of the acrylate-acrylatecoof the monomeric acrylates which are to be copolymerized and'the maximum foam-suppressing power thus readily arrived at, it r'nay also be p'ointedout that the same result may be achieved by preparing copolymers of alkyl acrylateswtih other mo'nomers which are copolymerizable therewith. In general, the Weight proportion ofthealkyl acrylate content of .these' copolymers should beat least 50%. The general princ'iples'to be employed'in cornbining monomers in order to obtain effective antifoaming I propertieswhen dissolved inany hydrocarbon oil are as;

--foll oWs:

Methyl and ethyl acrylate homopolyrn'ers ashas al-ia ready been pointed out are generally too oilinsolublej to.

Copolymers containing a I polymers may be controlled by appropriate selection;

omer selected should be one which in the homopolymeric form possesses little or no oil-solubility, Examples of these insolubility-promoting monomers are: acrylonitrile, methacrylonitrile, the lower alkyl methacrylates such as methyl, ethyl or propylmethacrylates, the lower vinyl esterssuch as vinyl acetate or vinyl'propionate and the lower alkyl maleates, fumarates, or itaconates, such as for example, the methyl or ethyl esters thereof.

That the oil solubility of polymers can be regulated by selecting monomers whose homopolymers have varying oil solubilities is generally recognizedfin the art. Thus,

according to Port et a1. (ind. Eng. Chem. 43, 2106-7 flf twomonomers are available and the homopolymer of one-is highly soluble and that of the other is insoluble in petroleum oils, then the copolymers should be expected" to'have a-graded solubility! lso,,in the 'Tutwiler Patent No. 2,637,698, there are prepared copoly'mers having a desired degree of oil. solurial is governed to a considerable extent by the ratio ofthe alpha methylene dicarboxylic esters; which. supply short side chains to the vcopolyrner, to theal'pha,beta unsaturated monocarboxy esters, which supply long side chains to the copolymer employed in the copolymeriza- I tion reaction.

For somepurposesextremelyoil-soluble polymers are desired for incorporation into the oil.., This is particuacrylates is increased-by copolyrnerization with a mu clearly al cylated styrene, the homopolyrners of: which are likewise very 'oil soluble. Such increase of oil solubility is shovvn in the Gleason -U.S. PatentfNo. 2,366,517 and the Harrison-US. Patent No; 2,593,444. Styrene or 'a nuclearly-allgylated styrene may'also be employed with a lower allryl acrylate such as ethyl' or methyl acrylate, whereby there areobtained copolymers of moderate .solubility. Veryhighly oil soluble acrylate copolymershave g also heenprepared by polg' rnerizing a mixture of a higher alliyl acrylate and a higher vinyl ester such .as'vinyl lau rate, as in the Van Horne et al. U.S'.Patents Nos. 2,600, I While the vinylesters generally give homopolyhers of low solubility the lower esters being practically oil-insoluble, vinyl esters in which the acid portion con .tainsifrorn 6 to'12 carbon atoms give .homopolymers.

Whose oil solubility increases with the carbon content of ;the monomensothat'the'degree of solubility of the acrylate-vinyl ester copolymer is a fun uon of the alk-yl chain length of each of the two esters and the proportion of the insolubilizing:solubilizing monomer used. In the Dittmar 'et al. U.S. Patent No.- 2,232,595 the solubility of acrylate polymerizing monomer; if any. s Variationin solubility of'a copolymer to fit individual requirements is a commonly employed procedure in the.

, art.

Concerning present day'practices in this respect Spurl'in '(I. Polymerjficience .3, 734 (1948)) makes the'se remarks about altering apolymer to secure a desiredde 'gi ee oi'solubility: I s f ii -it is desirable to Worl; with polymer solutions for either commercial or scientific purposes, it is frequently more desirable to alter the polymer for the best balance of solubility and physical properties than to go to great effort to use an available material. Manufacturers have long been conscious of this, and customarily supply materials tailored to fit individual application. Because of the wide variation of solubility characteristics that is deliberately introduced by the manufacture of copolymers and cellulose derivatives, it is usually wise to consult the manufacturers literature for detailed solubility characteristics.

Numerous examples of useful copolymers having the oil solubility of homopolyrners of alkyl acrylates having 3 to 6 carbon atoms will be given; and since tailoring of copolymers for the purpose of conferring thereto certain solubility characteristics is an established practice in the art, formulation of other alkyl acrylate copolymers having the desired degree of oil-solubility will present no problem to those skilled in the art.

' The presently useful alkyl acrylate polymers may be prepared by methods generally known to the art. The polymerization may be effected in mass, emulsion or solution in the presence of a free-radical liberating agent as catalyst and in the presence or absence of known polymerization regulators. When effected in mass, the monomer, or mixture of monomers, is simply maintained in the presence of the free-radical liberating agent, advantageously with agitation, and at temperatures of from, say,

C. to 130 C. until the polymerization is substantially completed. When the polymers are formed by emulsion polymerization methods, an emulsion of the'monomer components is made in an aqueous solution using suitable emulsifying agents such as soap or an alkyl-substituted sulfosuccinate, and the emulsion is then subjected to a polymerizing temperature which may vary from 25 C. up to the boiling point of water.

In solution polymerization, the monomer or monomers are dissolved in an inert liquid, and the resulting solution is agitated, preferably in the presence of a polymerizing catalyst at temperatures of from 25 C. to the boiling point of the solution to effect copolymerization of said mixture. Solvents which may be employed are generally substantially neutral organic liquid media, e.g., aliphatic, aromatic alkyl aromatic or alicyclic hydrocarbons such as hexane, benzene, ethylbenzene or cyclohexane; ketones such as methyl ethyl ketone or acetone, esters such as ethyl acetate or methyl propionate; chlorinated hydrocarbons such as carbon tetrachloride or chloroform;

ethers such as ethyl ether or dioxane. Since the polymers are used as oil additives, it is advantageous to effect the polymerization in a solvent which has no deleterious effect on the hydrocarbon oil to be treated, so that the {resulting solutions of polymer may be added directly to said oil without first having to separate the polymer from the reaction media.

- The presently useful alkyl acrylate polymers are very advantageously prepared by conducting the polymerization in the presence of polymerization modifiers, whereby the solubility of the polymers may be further regulated. As modifiers there may be used such well-known chaintransfer agents, telomerizers or regulators as the alkylmercaptans, e.g., tert-butyl mercaptan or ndodecyl mercaptan; the polyhaloalkanes such as carbon tetra chloride, chloroform or bromoform; the nitroalkanes such as nitroethane or 2-nitr0propane; liquid hydrocarbons such as toluene, ethylbenzene, or kerosene, etc. The chain terminating agent maybe used as a solvent during the reaction or it may be incorporated with an extraneous solvent, e.g., dioxane, acetone, parafiin hydrocarbons, etc.

The generally known polymerizing catalysts may be employed in preparing the polymers. There may be used, for example, such organic peroxidic compounds as acetylfben'zoyl,lauroyl or stearoylperoxide and tertbutyl or cumene hydroperoxide; inorganic per-compounds such as hydrogen peroxide, sodium perborate, or potas sium persulfate, diazo compounds such as azo-bis-isobutyronitrile, alpha, alpha'-azodiisobutyramide, etc.

The preparation of the useful polymers may also be carried out without the use of catalysts, e.g., by thermal polymerization.

The polymerization reaction may be effected batchwise, e.g., by agitating the solutions at increased temperatures, say at 110 C., until reaction has been completed, or continuously, i.e., by constantly removing the polymer while replenishing one or both of the monomers and/or catalyst and regulating agent. When operating batchwise, the reaction product, i.e., the polymer may be separated from the reaction mixture by distilling off the solvent and any unreacted starting material; however in practice, separation of the polymer is not generally necessary. Instead, the reaction mixture, comprising a solution of the polymer in the solvent, may be used directly as the antifoaming additive.

The present polymers areetfective antifoaming agents when they are employed in very low proportions, i.e., in amounts of less than 0.06 percent by weight, based on the weight of the total hydrocarbon oil composition. From .001 percent to .01 percent of the polymers is preferred, but may be varied depending upon the nature of the oil, amounts less than 0.04 percent by weight usually being sufiicient. Heavy oils and oils containing foaminducing adjuvants require more of the polymers than do base oils with lesser foaming characteristics.

The antifoaming effect of the present acrylate polymers is not materially affected by the presence of other adjuvants in the oil. Since the acrylate polymers are present in the oils in oily very small quantities, the use of even very acidic or very basic adjuvants in the oil has substantially no effect on the antifoam additives. Hydrocarbon oils containing the present antifoaming agents are stable when stored over long periods of time and also when subjected to heat and pressures representative of conditions encountered under operating conditions.

Hydrocarbon oils which are rendered substantially antifoaming by incorporation therein of quantities of less than 0.06 percent of the present polymers are synthetic or petroleum stocks of varying viscosities such as lubricating oils for internal combustion engines and motors, diesel fuels and lubricants and pressure transfer media, e.g., industrial lubricants, process oils, hydraulic oils, turbine oils, cutting oils, fluid greases, gear oils, shock absorber oils, spindle oils, journal bearing oils, pneumatic tool lubricants, etc. They may be synthetic or natural hydrocarbons of any type, i.e., paraflinic, naphthenic, aromatic or blended.

. Of particular interest is the usefulness of the present normally fluid acrylate polyers as antifoaming agents for lubricating compositions containing foam-inducing additives. As will be shown hereinafter, the present polymers retard foaming oflubricating oils containing additives which ordinarily tend to'increase the foam-susceptibility of base oils. Thus, theacrylate polymers function very efficiently as antifoaming agents for hydrocarbon lubricants containing detersive and pour-point depresisng additives generally, and particularly such detergents as the metal salts of aliphatic, cyclo aliphatic, aromatic and aromatic-aliphatic compounds containing as substituents at least one salt-forming radical, and a hydrocarbon chain of at least 4 carbon atoms. The structure and efficiency of some of such additives are described on pages 169-176 of the book Motor Oils and Engine Lubrication, by Carl W. Georgi, published by Reinhold Publishing Corporation, New York, 1950. As illustrations of such detergent additives may be mentioned aluminum, calcium or lithium salt of wax-substituted phenoxyphenol, the barium of wax-.

,7 i V substituted, sulphated hydroxydiphenyl sulfide, etc. The present acrylates may also be used as foam-suppressing additives for oils containing detersive additives such as the Wax-substituted benzene sulfonates, the petroleum sulfonates, or salts of alkylhydroxyphenyl sulfides. V .The present acrylate polymers are also efficient anti- The residues were low- The average 'molecular through a Vigreux column. molecular weight polymers.

weights given below were based on halogen content of the polmer determined by chemical analysis. The following preparations were tested for dcfoaming action in foaming agents for lubricant compositions containing ex- 200 cc. of Champlin base oil, employing the testing treme-pressure additives, such as the aromatic and all-zy1- Y procedure described above.

Polymer N one 710-720 From .3M Et acrylate, .73g. B2202, dz .6M

C014; 34 Ag. polymer, 9.24% Cl, 1535. From 263M Pr acrylate, .6g. B2 02, 1M 0014;

31g. polymer 2.99% Cl, M.W. 4750 From 2M Bu acrylate, 6.5g. B2202, 10M C014;

510g. polymer, 3.58% Cl, M.W. 3950 From 2M Bu acrylate, 7.5 cc. of 75% Gurnene hydroperoxide, 10M CClr; 220g. polymer, 2.13% Cl, M.W'. 6650 .s From .3M Bu acrylate, .GM 00h, .872g.

B2202; 37.1g. polymer, 2.65% 01, M.W. 5350. From .3M Bu acrylate, .9M .CHCls, 1.94g. Gumene hydroperoxicle; 392g. polymer, 1.50% Cl, MAV. 6690 I .From 30g. Bu aorylate,'l54g. C014, 1.5g. B2202; 32g. polymer, 3.98% 01, M.W. 3560 From 2M Bu aerylate, 10M (II-I013, 6.5g.

B2202; 505g. polymer, 2.08% Cl, M.W. 5130. From 8M Bu acrylate, M CHCla, 20.5g.

BzzOz; 982g. polymer, M.W. 5330 From 30g. Amyl acrylate'llQg. 011013, .6g.

BZzQ2; 28g.polymer, M.W. 5700 From .211M Am acrylate, 1.5g. BzrOr, 1M-

CCh; 31g. polymer, 4.6% Ci, M.W. 3100 From 211M Am aorylate, .Gg. BzzO'z, 1M

0014; 303g. polymer, 3.12% 01, M.W. 4550. From .193M hexyl acrylate .Gg. B2202, 1M

0014; 27.5g. p0lymer, 2.85%, C1, M.W. 4980. From .2M 2ethylhexyl aerylate, .6M C014,

z; 37.1g. polymer, 2.4% M.W. 5765 l 780 1 Reaction times days lnsteadpo! 48 hours.

aromatic compounds of from" 5 to 30 carbon atoms which contain a thiocarbonate group, e.g., chlorododecyl ethyl xanthate or chlorobenzyl methyl Xanthate; sulfocarbonates .such as trichlorobenzyl ethyl sulfocarbonate; trithiocarlimited, 'by the following examples:

Example 1 'The' effectiveness of antifoaming additives in hydrocarbon oils may be determined according to the procedure generally described in'Designation L12445 of the C9-- ordinating Lubricants Research. Committee or" the (30- j ordinating Research Council, New York. Briefly this procedure involves bubbling air or an inert gas such as nitrogen through the hydrocarbon oil to be tested employing standard apparatus and standard conditions and" reading the volume of foam produced.

A series of liquid polymeric alkyl acrylateswas pre pared as followsv; 1 i

Thealkyl acrylate was mixed wit-h, theqhalomethane.

indicated in the tablebelow andthe catalyst in the pro-f. portions shown below, and bottles of therespective mixtures werem aintained on a rotating raclcat a temperature of from 9095 C. for 48 hours. At the end. of that 75 In the presence of the indicated polymers at 50 ppm. 1

The above results show thatfwhile the antifoaming effect of the polymeric alltyl acrylates varies somewhat with the nature of the alkyl radical and with the average .molecular weight of the polymer, good anthoaming activity is obtained with the polymeric propyl," butyl, amyl and hexyl acrylates at even very low concentrations, i.e.,

at 50 parts of the polymer per million parts by Weight of Within the concentration' range-of frorn one to 50 parts per million (0.000170 to the oil 0.005% by weight).

- 0.005% the amyl acryiate polymer provides'the optimum antifoaming activity. l-loweven economy does not require these very low concentrations.

available polymeric propylacrylate'which is not soactive at the'verylow concentrations but which nevertheless possesses very good foaming efficiency at concentrations between'0.005% and 0.06% may often be employed more a'dvantageously as the antifoaming agent than the ex .trcmely active polymeric amyl. acrylate. a i

7 Under the test conditions each of these baseI oils 'g'ave V I Example'Z polymeric butyl acrylates on three .difierent oils. The testing procedure was substantially that employed in Exam- Plc 1, except that it was performedwith smaller'samplesj i.e.,' instead of using 200' cc. of the oil as in Example 1, there was used 30 ml. ofoil. T

In the following table the three different oilsused are: denoted as follows:

(l) Mid-Continent solvent refined SAE 30. V ('2) Mid-Continent'solvent refined SAE 10. 3 Champlin s nso.

a heavy foam in the 'a'bsenceof the antiioaming polymers:

Thus, the more readily Il -his example sh'owsthe antifoaming effect of various I vants, etc.

concentration the results shown in the following table were obtained:

as catalyst. The results obtained are shown in the following table.

Polymer Molecular Base Oil Results Weight Butylacrylate (prepared m 014) 2, 000 1 No foam Do 3, 52s 2 Do. 4, 807 2 Do. 5, 011 1 Do. 5. 352 1 D0. 1, 513 1 Do.

3, 253 2 & 3 Do. 4, 565 2 dz 1 D0. 5, 266 2 & 3 Do. Do 6, 690 1 Do. Butyl acrylate (prepared in 2, 899 1 Do.

OHBrz).

Do 3, 316 2 D0.

Example 3 Stability of various halomethane chain-terminated poly- 'meric alkyl acrylates in Champlin 30 oil under conditions of ordinary storage was determined by storing for days at room temperature samples of oil containing the respective polymers and then submitting the stored samples to the antifoaming testdescribed in Example 1. No foaming Was observed vwith samples containing 5 parts per million of the following polymers (see Example 1 for polyme preparation) Butyl acrylate, CHCl terminated. Mol Wt.=5130 Amyl acrylate, C01 terminated. Mol Wt.=4550 Amyl acrylate, OHCl terminated. Mol Wt.=5700 ,Similar results are obtained with oils containing not only the above antifoaming agents but also other lubricant additives, e. g., gear oil-s containing extreme pressure adju- Example 4 Employing the testing procedure described in Example 1 there was determined the antifoaming effect of some merca-ptan-terminated, polymeric butyl and amyl acrylates when employed in concentrations of from 2 parts to 50 parts of the polymer per million parts of Champlin oil. The polymers employed were prepared by heating for 48 hours at 90-95 C., thirty grams of the indicated acrylate and the indicated quantities of tert-butyl me-rcaptan in The above results show that while the antifoarning effect of the mercaptan-terminated polymeric alkyl acrylates varies with the quantity of mercaptan employed and thus with the average molecular weight of the polymer, as indicated by sulfur-content, good antifoaming activity is obtained with the polymers at even very low concentrations, i.e., at less than 50 parts of the polymer per million'parts by weight of the oil (less than 0.005% by weight). At the concentrations of less than 20 parts per million (0.002%) polymers having a sulfur content of less than 1.0% provide the optimum ant-ifoam activity.

Example 5 Stability of various mercaptan-termina-ted polymeric alkyl acrylates in Champlin 30 oil under conditions of ordinary storage was determined by storing for 15 days at room temperature samples of oil containing the respective polymers and then submitting thestored samples to the antifoaming test described in Example 1. No foaming was observed with samples containing 5 parts per million of the following polymers:

Polymeric butyl acrylate, terminated with terL-dodecyl mercaptan, and containing 0.38% sulfur.

Polymeric butyl acrylate, terminated with tertwbutyl mercaptan, and containing 0.16% sulfur.

Polymeric amyl acrylate, terminated with tert.-butyl mercaptan, and containing 0.12% sulfur.

Example 6 Employing the testing procedure described above there was determined the antifoaming effect of. polymeric butyl or amyl acrylates, prepared in toluene, when employed in concentrations of from 2 parts to 10 parts of the polymer per million parts of a Champlin 30 base oil. The polymers employed were prepared by heating for 48 hours at C. the indicated acrylate in toluene in the proportions shown below, and in the presence of benzoyl peroxide as catalyst. The viscosities shown below are 10% cyclohexanone specific viscosities at 25 C. The

benzene solution and in the presence of benzoyl peroxide 6() results obtained are shown in the following table:

. a I 7 1 Curnene hydroperoxide employed instead of benzoyl peroxide.

2 1 g. of cumene hydroperoxide and l g. of benzoyl peroxide.

1 l The above results show that good antifoaming activity is obtained with the polymers at very low concentrations, i.e., at less than 10 parts of the polymer per million parts by weight of the oil (less than 0.001% by weight).

Example 7 Polymeric butyl acrylate, specific viscosity =1.65.

' Polymeric amyl acrylate, specific viscosity=2.13.

Example 8. 1 r

Butyl and amyl acrylate were polymerized while dissolved in benzene. Reaction mixtures comprising 30 g. of either butyl or amyl acrylate, 92 g. of benzene and 0.3 g. of benzoyl peroxide were heated for 48 hours at 90 C. Removal of unreacted solvent and monomer gave 29.5 g. of a polymer in the case of butyl acrylate and 28 g. of a polymer in the case of amyl acrylate. Additive concentrates consisting of 2 g. of the polymer dissolved in 18 cc. of mineral spirits were prepared and added to Champlin SAE 30 oil. Employing the testing procedure of Example 1, the following results were obtained:

Foam (ml), after 5 Min. (Additive in p.p.m.) Polymer None 715 20 10 5 2 Butyl aerylate 10 20 200 Amyl acrylate 10 20 Example 9 244 g., and the diluted material was employed as the autifoam additive for Champlin SAE 30 oil. Assuming complete polymerization of the monomers, eachsolution was taken to be a 12.3 percent by weight concentrate of.

the polymeric acrylate. Employing the testing procedure of Example 1, the following results were obtained with the respective polymer solutions:

. Foam (ml) at Min. (Polymer in p.p.m.)' Polymer I None 715 5 2 Butyl aerylate 0 0 Butyl acrylate 1 0 0 20 Amyl acrylate 0 10 50 mill.

Example 10 V A mixture consisting of 256 g. (2- moles, 284 cc.) of butyl acrylate,. 1540 g; (10 moles, 965 cc.) of carbon tetrachloride and 14.25 g. of 72 percent cumene hydroperoxide (4 percent by weight of pure hyd'roper'oxide f based on the acrylate) was charged .to 8 small bottles (160 cc. each). These were maintained at 9 5 for 42 Reaction 1 Also present, 1.0% tert-butyl mereaptan, based on weight 01' monofoaming effect of a polymeric .amyl acrrylate.

I ing the solvent from the resulting reaction product.

- Champlin' 30 oil was incorporated with the additive to 12 hours. The reaction mixtures were then combined and the whole was stripped to yield 202 g. of the substantially pure polymeric butyl acrylate. In order to prepare an antifoam concentrate, 100 g. of the stripped product was dissolved in 300 g. of kerosene and then further diluted to 20 percent solids by the addition of 100 g. of toluene. The resulting concentrate was then added to aircraft engine oil 120 in a quantity to give 10 parts of polymer per million parts of oil, and the foam susceptibility of the resulting'oil was determined as described in Example 1, except that instead of using 200 cc. of oil, 40 cc. of the oil was employed for the test. No foam was obtained at 'the 10 ppm; concentration (0.001 percent) whereas 7 the untreated oil gave cc. of foam under the same test conditions. I

Example 11 Into a flask equipped with stirrer and'thermorneter there was placed 225 g. of butyl'acrylate and 750 g. (865 cc.) of toluene. The reaction mixture was brought to a temperature of C. Within 35 minutes and there was initiated the portionwise additiouofa catalyst solution consisting of 6.25 g. (7.3 cc.) of commercial 72 percent cume'ne hydnoperoxide diluted with'toluene to 25 cc. The first portion added was 5 cc.; the remaining20 cc. was added in 2-cc. portions at intervals during the subsequent 3.2 hours, during which period the pot temperature was maintained at about C. Heating at 109.0-109.5 C. was continued for an additional 3 hours, at which time polymerization wa substantiallycompleted. Refractive index determinations on samples of the reaction mixture withdrawn at intervals during the run showed 55 'percent polymerization after 1.25 hours and 79 percent after 2 hours.

The reaction mixture was then stripped at a maximum Example 12 For still anothertest with air-craft engine oil 120,amy1

acrylate was prepared in carbon tetrachloride as follows:

A mixture consisting of 480g. of amylacrylate, 2464 g. of carbon tetrachloride and 9.6 g. .of benzoyl' peroxide was charged to 16 bottles, and the bottles were tumbled" for 40 hours at a temperature of 95C. The contents of all were combined, and the combined material stripped at a maximum pot temperature of C./3 mm. to"

centration of 10 parts of polymer per million partsrof oil.

It was similarlyj efficient-when tested with Champlin SAE 30 oil. j v I Example 13' V V 'This example shows .the efiect of heat on the anti- The polymer was prepared by tumbling for 48 hours a mixture consisting of 30 g. of the acrylate, 154 g. of carbon" tetrachloride, and 0.15 g. of benzoyl peroxide, and removgive a concentration of additive of ten .parts per million,

andthe treated oil was tested for foaming substantially .as d'escribed in Example 1, except that tests were made :at the various temperature shown below and that they wer'e erformed on a small scale, i.c., insteadof using 200 cc. V of oil,.the volume of test sampleplusbubbler was 35 cc. 7

1.3 The following results were obtained with the untreated and treated oils.

' Butyfacrylate, C014 terminated, M01

Foam (00.), at 5 Minutes Temperature, C.

Untreated Treated Oil Oil Example 14 A Cha-mplin SAE 30 oil was incorporated with 4% by weight of a detergent additive and samples of the compounded oil thus obtained were then admixed with various polymeric acrylates in concentrations of from 5 parts to 59 parts of the polymer per million parts of the detergent containing oil. The detergent additive which was employed was a barium salt of an alkyl aromatic s-ulfonic acid in which the alkyl radical has from 22 to 30 carbon atoms and will be hereinafiter des gnated as D1. The polymers employed were prepared by heating the indicated alkyl acrylate for 48 hours at 90-95 C. in the presence of the indicated chain-terminating agent, e.g., an alkyl'benzene, alkyl rnercaptan or polyhalomethane and in the presence of benz-oyl per-oxide as catalyst. Samples of the oil containing 4% by weight of D-1, and the respective polymeric acrylates in the quantities shown below were submitted to the testing procedure described in Example 1 in order to determine the antifoaming effect of the polymers. The results obtained are shown in the following table:

Polymeric amyl acrylate, toluene terminated, 10% cyclohexanone. Specific Viscosity=2il3 Polymeric amyl acrylate, butyl mercaptan terminated.

Percent S=0.12

Example 16 A 30 grade, 93 VI. base oil was incorporated with 6.5% by weight of an extreme pressure additive comprising chloronaphtha alkyl xanthate (chlorinated naphtha in which only a part of the chlorine has been substituted by an alkyl xanthate group) and a sample of the compounded oil was admixed with a carbon tetrachloride terminated polymeric butyl acrylate in a concentration of 200 parts i of polymer per million parts of'compounded oil by weight.

Evaluation of the foam-susceptibility of the resulting sample employing the testing procedure described in Example 1 showed no foaming after 5 minutes bubbling time, whereas oil containing only the xanthate in absence of the polymer, gave considerable foam when submitted to the same test.

Example 17 A 30 grade, 93 V1. base oil was incorporated with 6.5% by weight of the chl-oronaphtha alkyl xanthate of Foam (ed) at 5 min. (Additive in ppm) Propyl acrylate, C014 terminated, M01

l) Butyl acrylate, tert.-butyl mereaptan terminated, percent S=0.25 0 Butyl aerylate, toluene terminated, specific viscosity= 1.65 1 0 0 Butyl acrylate, CHCI; terminated, M01

Wt. 5,1 10 0 Amyl agrylate, C014 terminated, M01 Wt.

Amyl aerylate, toluene terminated, Specific viscosity=2.18 Amyl aerylate, tert.-butyl mercaptan terminated, percent S =0.12 Hexyl acrylate, 0C1; terminated, M01

1 10% cyclohexanone.

Example 15 Ohamplin' 30 oilwas heat-blended with 4% by Weight of the detergent additive D-'1 (see Example 14), andto samples of the compounded oil were added 5 parts per million partsof compounded oil of the various polymeric amyl acrylates shown below. The polymers were prepared as shown in Examples 1, 4 and 6. The samples were then tored at a temperature of 25 C. for 15 days. At the end of that time each sample was submitted to the testing procedure described in Example 1 in order to determine the effect of storage on the antifoaming properties of the polymeric amyl acryla-tc. No foam was observed with samples containing 5 ppm. of the following polymers: I

Example 16 and a sample ofthe compounded oil was admixed with a normally fluid, carbon tetrachloride terminated polymeric amyl acrylate in a concentration of parts of polymer per million parts of compounded oil by weight. ploying the procedure described in Example 1, showed no foam at a 5-minute bubbling time.

Example 18 To 93.25 parts by weight of a 30 grade, 93 V1. oil there was added 6.75 parts by'weight of an ER additive comprising predominantly the chloronaphtha alkyl xanthate of Example 15 together with minor proportions of added the polymeric amyl acrylate ofExample 16 in a Foaming tests on the resulting sample, em-v Example 19 Samples of the compounded oils of Examples 16-18, i.e., samples of hydrocarbon oil containing the E.P. additives and the polymeric acrylates were stored for 60 days. No foaming was observed when the stored samples were submitted to the foaming test described in Example l.

Example 20 This example shows the. effect of various acrylateacrylate copolymers onthe foaming tendencies of hydrocarbon oils.

The acrylate mixtures shownbelow were copolymerized in 100 cc. of carbon tetrachloride by maintaining bottles of the solution on a rotating rack (43 r.p.m.) for 48 hours at 98 C. Benzoyl peroxide (1% based on the Weight of the monomer mixture) was used as catalyst. The copolymers were recovered by stripping off the solvent, and were incorporated into a Champlin 30 oil in the concentrations shown below. The following foam test data were obtained using the evaluation procedure The reaction product, comprising a solution of the 70:30 Z-ethylhexyl acrylate-ethyl acrylate'c opolymer in the kerosene was used directly as an antifoam additive. Incorporation of the solution into 'a Champlin 30 oil in a quantity corresponding to 10 parts of copolymer per million parts of oil and testing of the treated oil by the method of Example 1 showed no foam at 5 minutes. 7

Example 22 A mixture consisting of 210 g. (1.14 moles) of 2- ethylhexyl acrylate, 90 g. (0.9 mole) of ethyl acrylate, 1575 g. of carbon tetrachloride and 5.83 g. (1.94 percent by weight based on total 'acrylates) was charged to 9 bottles. These were then maintained on a rotating rack at 43 r.p.m. for 40 hours at 95 C. After combining the reaction mixtures the whole was stripped to give 311 g. of the substantially pure, viscous liquid Z-ethylheXyl acrylate-ethyl acrylate copolymer. In order to prepare a concentrate, 150 g. of the liquid copolymer was diluted with 150 g. of toluene and 450 g. of kerosene to give an additive havinga percent by weight copoly mer content. This was tested with aircraft engine oil 20 as in Example 10. No foam was obtained at a concentration of 10 parts 1n Example 1. 7 of copolymer per million parts of 011.

Copolymer Reactants Av. Foam (00.) at 5 Allryl Min. (Copoly- Chain mer, p.p.m.) Length Acrylate G. Mole Aerylate G. Mole Molar Basis 40 10 2-ethylhexyl .130 Ethyl a .060 6.1 0 0 .114 Ethyl 9 .090 5.4 0 0 130 PropyL 6 053 6. 5 0 390 164 Propyl 4. 5 039 5. 4 0 0 Example 21 Example 23 A fluid alkyl acrylate-alkyl acrylate copolymer having 40 This example shows the antifoaming effect of various an average alkyl chain length of 5.35 carbon atoms on a molar basis, and substantially the oil-solubility-of amyl 2-ethylhexy1 acrylate-ethyl acrylate copolymers. The copolymers were prepared in carbon tetrachloride solution and in the presence or" about 2 percent of the monomer weight of benzoyl peroxide, polymerization being effected by agitating the solutions at 43 rpm. for 65 hours at 80 C. The copolymers were recovered'by stripping off the solvent and any unreactedmonomer. Foam tests of Champlin SAE 30 oils which had been incorporated with the copolymerswere conducted by the method of Exthermometer', and the mixture was heated to a tempera- 5t) ample 1. The following resultswere obtained:

Copolymer React-ants Av. alkyl Foam (mL) Alter 5 Min.

chain M01. (Copolymer in p.p.m.) Z-Ethylhexyl Ethyl length 71;. of

acrylate acrylate molar Cobasis polymer G. Mole G. Mole I 4O 2O 10 5 2 ture of about 100 C. withinonehour. The temperature was maintained at from 97 C. to 102 C. for an additional 5.7 hours. About the middle of the heating period an additional l-gram portion of benzoyl peroxide was added. Atintervals, during the heating period, samples of the reaction'mixture were removed in order to "note the reaction progress. Refractive index determinations made on the samples showed 54 percent polymerization at the end of 2 hours, 83 percent at the end of 4 hours and 100 percent polymerization at the end of 6.7 hours, at which time heating Was discontinued.

Theabove datashow that most efficient antif-oaming effect is imparted to this oil by copolymers prepared from 65 weight percent to weight percent of the 2-ethylhexyl prepared polymeric ethyl acrylate gave a foam value of V 705 m'lfat the50 p.p.m. concentration when tested by the same procedure. The base oilhad a foam value of 71S mLin the absenceof any additive.

17 Example 24 This example describes the preparation and usefulness of a 58.3:4l.7 (molar ratio) n-octyl acrylate-methyl acrylate .copolymer having an average alkyl chain length of 5.07 carbon atoms.

A mixture consisting of 75 g. of n-octyl acrylate, 25 g. ofmethyl acrylateand 300 g. of a liquid hydrocarbon known as Stoddard Solvent was heated to 100 C. and there were added to the heated mixture four portions of benzoyl peroxide(0.5 g. each) at 45 minute intervals. Heating was continued 45 minutes after the final catalyst addition so that the total heating period at 100 C. was three hours. The reaction mixture, comprising a 25 percent solution of 75:25 (weight ratio) n-octyl acrylatemethyl acrylate copolymer completely inhibited the foaming tendency of a Champlin 30 oil when added to the oil in a concentration equal to 100 parts of additive to a million parts of oil.

' Example 25 Using the-procedure of Example'24, there was prepared a 20 percent solution of 48.5 :5 1.5 (molar ratio) decyl acrylate-methyl acrylate oopolymer having an average alkyl chain length of 5.37 carbon atoms. re reactants comprised 70.0 g. of decyl acrylate, 30.0 g. of methyl acrylate, 400 g. of Stoddard Solvent and 1.50 g. of benzoyl peroxide. The total heating time at 100 C. was 6 hours.

The reaction product, comprising a solution of a 70:30 (weight ratio) decyl acrylate-methyl acrylate copolymer in the kerosene was used directly as an antifoamant in a 30 grade oil, whereby a quantity corresponding to 100 parts of the copolymer per million parts of oil completely eliminated the foaming tendencies of the oil.

Example 26 A 29:71 (molar ratio) copolymer of n-lauryl acrylate and ethyl acrylate, having an average chain length of 4.9 carbon atoms, was prepared substantially according to the procedures of Example 24, except that there were used equal parts by weight of the respective acrylates and that a kerosene known to the trade as Skellysolve S was used as solvent. The final reaction product comprised a 40 percentsolution of the copolymer in Skellysolve S.

'When used as anantifoamant in Champlin 30 oil, complete inhibition of the oil to foaming was effected at a concentration of 100 parts of additive to a million parts of oil. V

Example 27 tion 60:40 nonyl acrylate-ethyl acrylate copolymer (or 43:57 molar ratio nonyl:ethyl copolymer) having an average alkyl chain length of 5 carbon atoms was used directly as an antifoamant and completely stopped the foaming of a 30 grade an at a concentration of 100 parts per million.

Example 28 example shows theiantifoaming effects on Champ- 30 base oil of copolymers of n-butyl or amyl acrylate and styrene. The copolymers were prepared by maintaining'fbottled solutions of the monomer mixtures for 48 hours on a rotating rack 43 r.p.m.) at a temperature of 90-95 C. In one case the monomer mixture consisted of 27 g.of n-butylacrylate and 3 g. of styrene and in another experiment the monomer mixture consisted of Heating at 100 C. was con 18 25.5 g. of amyl acrylate and 4.5 g. of styrene. In each experiment 100 cc. of carbon tetrachloride was used as solvent and 0.6 g. of benzoyl peroxide was employed as catalyst. The monomers used were employed as received, i.e., without removing any inhibitor present.

In each case reaction mixtures resulting from the polymerization were diluted to 200 cc. with toluene. The diluted materials comprising solutions of the respective copolymers were employed as the antifoam additives. This procedure eliminated the necessity of isolating the polymer (stripping operation) and re-dissolving it in a suitable solvent for use as a concentrate. The quantity of diluted material employed was based on the assumed complete copolymerization of the monomers. Thus, in each case the 200 cc. of toluene-diluted material was assumed to contain 30 g. of copolymer, 0.01 cc. of the diluted material containing 0.0015 g. Accordingly, addition of 0.01 cc. of the diluted material to 3738 cc. of base oil corresponded to the addition of approximately 50 parts of copo-lymer per million parts of oil. Samples of Champlin 30 base oil which had been thus incorporated with varying amounts of the respective copolyme-r were tested for foaming as described in Example .1, except that instead of using a 200 cc. sample of oil, 37 cc. of oil was used for each test. No foam was observed at the concentration of 50 parts per million of the respective copolymers; whereas the oil, alone, gave about 70 cc. of foam under the same test conditions.

Example 29 This example shows the antifoaming effect of copolyiners of various alkyl acrylates and acrylonit-rile. Employing the copolymerization procedure of Example 28 copolymers were prepared from the following monomer mixtures:

27 g. Z-ethylhexyl acrylate and 3 g. acrylonitrile 27 g. n-butyl acrylate and 3 g. acrylonitrile 25 .5 g. amyl acrylate and 4.5 g. acrylonitrile Testing of the Champlin 30 base oil as is Example 28 showed no foam for respective test samples containing 50 parts per million of copolymers'prepared from the above mixtures.

Example 30 27 g. 2-ethylhexyl acrylate and 3 g. methyl inethac-rylate 25.5 g. 2-ethy1hexyl acrylate and 4.5 g. methylmethacrylate V 27 g. n-butyl acrylate and 3 g. methyl methacrylate 27 g. amyl acrylate and 3 g. methyl methacrylate Copolymers obtained 'from the above monomer mixtures showed no foaming at 50 parts per million when tested with Champlin 30 base oil as in Example 28.

Example 31 This example shows the antifoaming efiect of copolymers of various acrylates and methacrylonitrile. The polymerization was effected as in Example 28 except that in this instance the following monomer mixtures wer used:

28.5 g. 2-ethylhexyl acrylate and 1.5 g. methacrylonitrile 27 g. Z-ethylhexyl acrylate and 3.0 g. methacrylonitrile 27 g. butyl acrylate and 3 g. methacrylonitrile 27 g. a-myl acrylate and 3 g. methacrylonitrile Addition of the above copolymers, respectively, to Champlin 30 base oil showed no foaming at a concentration of 50 parts per million when tested as in Example 28. i

1 a I. Example 32 This example shows the antifoaming effect of copolymers of various acrylates and vinyl acetate of isopropenyl acetate. The polymerization was'effected as in Example 28 except that instead of employing only carbon tetrachloride as solvent, a mixture of 100 cc. of toluene and 100 cc. of carbon tetraehloride'was used, and that in this case the following monomer mixtures were used:

24 g. 2-ethylhexyl acrylate and 6 g. vinyl acetate 21 g. Z-ethylhexyl acrylate and 9 g. vinyl acetate 27 g. butyl acrylate and 3 g. vinyl acetate 27 g. amyl acrylate'and 3 g. vinyl acetate 27 g. amylacrylate and 3 g. isopropenyl acetate No foaming was observed of Champlin 30 baseoil containing 50 parts per million, respectively, of. the copolyrners obtained from the above mixtures.

Example 33 Copolymers having the oil-solubility of polybutyl acrylate were prepared by heating for 48 hours at 90-95 C. mixtures of di-n-butyl maleate with n-butyl acrylate or n-amyl acrylate in carbon tetrachloride solution and in the presence of 'benzoyl peroxide as catalyst. Testing of the anti-foaming effect of the copolymers by the test proeedure of Example 1 gave the following values:

Example 35 This example shows that antifoaming amounts of a liquid polymeric amyl acrylate have substantially no elfect on oil treated therewith. ,The polymer was prepared as follows: 1

A mixture consisting of 240 g. of ainyl acrylate, 1232 g. of carbon tetrachloride andv 4.8 g. of benzoyl peroxide was charged to 8 bottles, and the bottles were maintained on a rotating rack (43 r.p.m.) for hours at 95 C. The

reaction mixtures were then combined, and stripped to 160 C./23 m m. There was thus obtained as residue 7 235 g. of the viscous, liquid polymeric amyl acrylate having an average molecular weight of 5250 as determined by chlorine analysis of this carbon tetrachloride-terminated polymer. A sample of a Mid-Continent solvent-refined SAE grad 10 oil containing 0.05 percent (500 ppm.) of the copolymer of this example was tested for viscosity and foaming as in Example 34. The viscosity value of the treated oil was 207.3 (S.U.S.) vs. 207.8 for the oil, alone. The foam test showed no foam for the treated oil, vs. a foam value of 70 ml. forthe untreated oil.

Example 36 This example compares the effect on oil foam of some Foam (ml.) at 5 Min. (Additive V Reactants Used, 5;. Av. in Parts Per Million of Oil) C014 M01. [M aleate Wt.

Acrylate Catalyst 7 None 50 10 V 5 2 QOOOOO Example 34 This example shows that antifoaming amounts 'of a liquid Z-ethylhexyl acrylate-ethyl acrylate copolymer have substantially no effect on the viscosity of an oil treated therewith.

A 70:30 2-ethylhexyl acrylate-ethyl acrylate copolymer was prepared as follows: A mixture consisting of 140 g. (0.75 mole) of Z-ethylhexyl acrylate, 60 g. (0.60 mole) of ethyl acrylate, 1050 g. of carbon tetrachloride and 3.89 g. of benzoyl peroxide was charged to 6 bottles, which were then tumbled for 48 hours at 95 C. Removal of solvent from the combined reaction mixtures at 150 C./10 mm. gave 196 g. of the substantially pure Z-ethylhexyl acrylate-ethyl acrylate copolymer having an average molecular weight of 6900 as determined by chlorine analysis of this carbon tetrachloride-terminated product, and an average alkyl chain length of 5.35.

In order to determine if the copolymer caused any appreciable viscosity change in the oil, an untreated sample of a Mid-Continent, solvent-refined SAE grade 10 oil and a. sample of the same oil containing 0.05 percent (500 ppm.) of the copolymer of this example were prepared, and the viscosity of the specimens determined at 100 F., employing the American Society for Testing Materials method D-445-46T. The untreated oil was found to have a viscosity (S.U.S.) of 207.8, and the value for the treated polymeric alkyl acrylates with that of some methacrylates.

Employing the polymerization procedure generally polymeric described in Example 1, polymerization of monomeric' alkyl acrylates or rnetha'crylates was effected in carbon tetrachloride solution to give polymers having the molecularweights shown below. Evaluation of the antifoaming efficiency of the polymers in Champlin 30 base oil, using "the evaluation procedure of Example 1 for tests at the oil was 207.9. Evaluation of the foam susceptibility of the untreated and treated oil, using 1 the procedure of Example 1 except that instead of using 200 cc. of the oil, 37 cc. of oil was employed for each test, gave a foam of cc. for the untreated oil and no foam for the treated oil. acrylatecopolymer confers antifoam property to hydrocarbon oils without causing any appreciable change in the viscosity characteristics of the oil.

From these data it is apparent that the acrylate- Amyl methacrylate, mol. wt. 5,450. l i

500 ppm. concentration, and the'procedure of Example 2 for tests at the 50 ppm. concentration gave the following results:

12 1 11 (00.) at 5 Min. O ymer 1J1 .111. Polymer Additive p 950 Over 70 ml. Amyl acrylate, mol. wt. 5,460.-- 0- 0., Hexyl acrylate, mol. wt. 3,130 Hcxyl methacrylate, mol. wt. 3,100

0 0. 660 Over 70731.

I This application is continuation-in-part of my application Serial No. 390,250 filed November 4, 1953," as a continuation-in-part of my application Serial'No. 281,680,

filed April 10, 1952 and now abandoned.

What is claimed is: a

1. A composition of matter of'r'educed foaming proper 7 t ies consisting essentially of a hydrocarbonf'oil' having foaming tendencies and aquantity' less than 0.06% by weight, based on the weight of said oil, said quantity being: sufficient to suppress said'foaming tendency b'ut insufiicient to modify substantiallyfihe viscosity characteristics of the oil, ofan' alkyl acrylate polymer having a molecular weight less than. 10,000 and selected from having the oil-solubility of (A) and containing at least 50% by weight of an alkyl acrylate in which the alkyl radical has from 1 to 18 carbon atoms with the balance 7 being a compound other than said acrylate and copolymerizable with the acrylate, the said compound being selected from the group consisting of alkyl methacrylates, styrenes, alkyl furnarates, alkyl maleates, alkyl itaconates, acrylonitrile, methacrylonitrlle and vinyl esters of aliphatic monocarboxylic acids.

2. A lubricant of reduced foaming properties consisting esentially of a hydrocarbon oil lubricant having foaming tendencies and a quantity less than 0.06% by weight based on the weight of said lubricant, said quantity -being sufficient to suppress said foaming tendencies but insuflicientto modify substantially the viscosity charac- 7 atoms in the alkylradicals of the copolymer molecule is at least 3 but less than, 7 on a molar basis and (C) a copolymer having the oil-solubility of (A) and containing at least 50% by weight of an alkyl acrylate in which the alkyl radical has from 1 to 18 carbon atoms with the balance being a compound other than said acrylate and copolymerizable with the acrylate, the said compound being selected from the group consisting of alkyl methacrylates, styrenes, alkyl fumarates, alkyl maleates, alkyl itaconates, acrylonitrile, methacrylonitrileand vinyl esters of aliphatic monocarboxylic acids.

3. A detersivehydrocarbon oil lubricant of reduced foaming properties consisting essentially of a hydrocarbon oil lubricant having foaming tendencies and comprising said lubricant, an oil-soluble metal salt as a detergent additive and a quantity less than 0.06'percent by weight of said lubricant, said quantity being sulficient to suppress said foaming tendencies but insuflicient to modify substantially the viscosity characteristics of the lubricant, of an alkyl acrylate polymer having a molecular weight less than 10,000 and selected from the class consisting of (A) a normally fluid homopolymer of an alkyl acrylate having at least 3 but less than 7 carbon atoms in the alkyl radical, (B) a normally fluid copolymer of two different alkyl acrylates in which the alkyl radical has from 1 to 18 carbon atoms and in which the average number of carbon atoms in the alkyl radical of the copolymer molecule is at least 3 but less than 7 on a molar basis and (C) a copolymer having the oil-solubility of (A) and containing at least 50% by weight of an alkyl acrylate in which the alkyl radical has from 1 to 18 cient to modify substantially the viscosity characteristics of the lubricant, of an alkyl acrylate polymer having a molecular weight less than 10,000 selected fromthe class consisting of (A) a normally fluid homopolymer of an alkyl acrylate, having at least 3 but less than 7 carbon atoms in the alkyl radical, (B) a normally fluid copolymer of two different alkyl acrylates in which the alkyl radical has from 1 to 18 carbon atoms and in which the average number of carbonatoms in the alkyl radical of the copolymer molecule is at least 3 but less than 7 on a molar basis and (C) a copolymer having the oil-solubility of (A) and containing at least by weight of an alkyl acrylate in' which the alkyl radical has from 1 to 18 carbon atoms with the balance being a compound other than said acrylate and copolymerizable with the acrylate, the said compound being selected from the group consisting of alkyl methacrylates, styrenes, alkyl fumarates, alkyl maleates, alkyl itaconates, acrylonitrile, methacry-- lonitrile and vinyl esters of aliphatic monocarboxylic acids.

5. A lubricant of reduced foaming properties consisting essentially of a hydrocarbon oil lubricant having foaming tendencies and a quantity of less than 0.06 percent by weight, based on the weight of said lubricant, said quantity being suflicient to suppress said foaming tendencies but insuflicient to modify substantially the viscosity characteristics of the lubricant, of a normally fluid homopolymer of an alkyl acrylate having at least 3 but less than 7 carbon atoms in the alkyl radical and the'homopolymer having a molecular weight less than 10,000.

6. A lubricant of reduced foaming properties consisting essentially of a hydrocarbon oil lubricant having foaming tendencies and a quantity of less than 0.06 percent by weight, based on the weight of said lubricant, said quantity being sufficient tosuppress said foaming'tendencies but insufficient to modify substantially the viscosity characteristics of the lubricant, of a normally fluid copolymer of two different alkyl acrylates in which the alkyl radical has from 1 to 18 carbon atoms and in which the average number of carbon atoms in the alkyl radical of the copolymer'molecule is at least 3 but less than 7 on a molar basis, the, copolymer having a molecularweight less than carbon atoms'with the balance being a compound other than said acrylate and copolymerizable with the acrylate, the said compound being selected from the group consisting of alkyl methacrylates, styrenes, alkyl furnarates,

alkyl maleates, alkyl itaconates, acrylonitrile, methacrylonitrile and vinyl esters of aliphatic monocarboxylic acids.

4. An extreme pressure-resisting hydrocarbon oil lubricant consisting essentially of a hydrocarbon oil having foaming tendencies, an extreme pressure-resisting additive, and a quantity of less than 0.06 percent by weight based on the weight of said lubricant, said quantity being suflicient to suppress said foaming tendencies but insufli- 7. A lubricant of reduced foaming properties consisting essentially of a hydrocarbon oil lubricant having foaming tendencies and a quantity of less than 0.06 percent by weight based on the weight of said lubricant, said quantity being sufficient to suppress said foaming tendencies but insufficient to modify substantially the viscosity characteristics of the lubricant of a copolymer possessing the oil-solubility of a normally fluid homopolymer of an alkyl acrylate having at least 3 but less than 7 carbon atoms in the alkyl radical, said copolymer containing at least 50% by weight of .an alkyl acrylate in which the alkyl radical has from 1 to 18 carbon atoms with the balance being a compound other than the acrylate and copolymerizable with the acrylate, the said compound being selected from the group consisting of alkyl methacrylates, styrenes, alkyl fumarates, alkyl maleates, alkyl itaconates, acrylonitrile, methacrylonitrile and vinyl esters of aliphatic monocarboxylic acids and said copolymer having a molecular weight less than 10,000.

8. The lubricant of claim 5 further defined in that said polymer is a normally fluid polymeric butyl acrylate.

9. The lubricant of claim 5 further defined in that said polymer is a normally fluid polymeric amyl acrylate.

10. The lubricant of claim 7 further defined in that said polymer is a normally fluid copolymer of 2-ethylhexyl acrylate and acrylonitrile consisting, by weight, of from to of copolymerized 2-ethylhexyl acrylate and 10% to 15% of copolymerizedacrylonitrile.

11. The lubricant of claim 7 further defined in that said polymer is a normally fluid copolymer of Z-ethylhexyl acrylate and methyl methacrylate consisting, by weight, of from 80% to 90% of copolymerized 2-ethylhexyl 25 acrylate and from 10% to 20% of copoly-rnerized methyl methacrylate.

12; The lubricant of claim 1 further defined in that the molecular weightof the polymer is no greater than 6900.

13.. The lubricant of claim 6 further defined in that .the

V foaming tendencies and a quantity' lessthan 0.1% by 15. The lubricant of claim 5 further defined in that Weight based on the weight of said lubricant, said quantity being sufficient to suppress said foaming tendencies but insufiic'ient to modify substantiallytheviscosity characteristics of'the lubricant, of a normally fluid copolymer' of Z-ethylhexyl acrylate and ethyl acrylate consisting by Weight, of from 65% to 75% of copolymerizedZ-ethylhexyl acrylate and 25 to 35% of copolymerized ethyl acrylate."

\ V 7 References Cited by the Examiner;

UNITEDSTATES PATENTS V 2,330,773 9/43 Zimmer 252-56 2,430,858 11/47 Borsoif et al 25252 2,600,448 6/52 Van Horne et a1. 25256 2,604,453 7/52 Popkin 252-56 DANIEL E. WYMAN, P rimary Exaininer. 

1. A COMPOSITION OF MATTER OF REDUCED FOAMING PROPERTIES CONSISTING ESSENTIALLY OF A HYDROCARBON OIL HAVING FOAMING TENDENCIES AND A QUANTITY LESS THAN 0.06% BY WEIGHT, BASED ON THE WEIGHT OF SAID OIL, SAID QUANTITY BEING SUFFICIENT TO SUPPRESS SAID FOAMING TENDENCY BUT INSUFFICIENT TO MODIFY SUBSTANTIALLY THE VISCOSITY CHARACTERISTICS OF THE OIL, OF AN ALKYL ACRYLATE POLYMER HAVING A MOLECULAR WEIGHT LESS THAN 10,000 AND SELECTED FROM THE CLASS CONSISTING OF (A) A NORMALLY FLUID HOMOPOLYMER OF AN ALKYL ACRYLATE HAVING AT LEAST 3 BUT LESS THAN 7 CARBON ATOMS IN THE ALKYL RADICAL, (B) A NORMALLY FLUID COPOLYMER OF AT LEAST TWO DIFFERENT ALKYL ACRYLATES IN WHICH THE ALKYL RADICAL HAS FROM 1 TO 18 CARBON ATOMS AND IN WHICH THE AVERAGE NUMBER OF CARBON ATOMS IN THE ALKYL RADICALS OF THE COPOLYMER MOLECULE IS AT LEAST 3 BUT LESS THAN 7 ON A MOLAR BASIS AND (C) A COPOLYMER HAVING THE OIL-SOLUBILITY OF (A) AND CONTAINING AT LEAST 50% BY WEIGHT OF AN ALKYL ACRYLATE IN WHICH THE ALKYL RADICAL HAS FROM 1 TO 18 CARBON ATOMS WITH THE BALANCE BEING A COMPOUND OTHER THAN SAID ACRYLATE AND COPOLYMERIZABLE WITH THE ACRYLATE, THE SAID COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF ALKYL METHACRYLATES, STYRENES, ALKYL FUMARATES, ALKYL MALEATES, ALKYL ITACONATES, ACRYLONITRILE, METHACRYLONITRILE AND VINYL ESTERS OF ALIPHATIC MONOCARBOXYLIC ACIDS. 